The invention concerns a combination of a plug and a socket for the connection of electrical lamps and electrical equipment, especially a combination which is also able to receive electrical power and which is suitable for all types of current.
A safety quick-connect unit for electrical lamps and equipment is shown in DE-OS No. 32 35 965. That unit consists of a plug and a socket, and the socket has a central, more or less cylindrical recess in which the electrical contacts are exposed, and into which a plug of corresponding cross-section can be inserted. The plug supports electrical contacts in the form of metal strips on its housing surface. A ground or neutral conductor is positioned in the center of both parts and the plug and the socket are connected by a bayonet connection.
This construction, however, has the serious disadvantage that in the central recess of the socket, the current-conducting contacts are exposed, so that inadvertent penetration with a finger can lead to an electrical shock and, thus, to injuries or burns. Accordingly, such a device represents a great danger for people, particularly for playing children, when the plug is removed. A further disadvantage is that the electrical connection with the socket or the contacts positioned on the socket is only able to be accomplished with difficulty, because the connection points are positioned outside and below the socket. Therefore, when for example the safety cap is removed or if the protective cap is damaged, the connection points are unsecured and can be damaged, and the insulation can also be damaged, so that dusting or other physical contact by the user ca result in the danger of injuries or burns.
The covering cap of the socket which is provided in this quick-fastening unit is changeable and is, therefore, relatively easy to remove.
In contrast the invention provides a plug and socket combination which is safe, can not lead to injuries from electrical shocks, is capable of compact construction, and in which all parts which conduct current or are electrically charged are protected against human contact and are accommodated in the housing of the combination. The combination in accordance with the invention is suited for all types of electrical devices, as well as for connections for surface and wall lamps, for plug and socket connections, for appliances such as standing lamps, pressing irons and the like and, because of the construction of the socket, can be advantageously used as a covered connecting socket which, when not in use, can be closed by a cap or a cover unit.
These advantages are achieved by way of a socket which comprises a body in which a bushing is centrally positioned which forms the neutral conductor and supports an axially movable, spring loaded disc with circularly arranged slot apertures positioned in a circle at a distance to each other. The apertures correspond to the current-conducting contacts in the body, which are surrounded and supported by a casing-shaped housing unit. The casing-shaped housing unit has groove-shaped recesses on its inside. The recesses accommodate projections on the plug for the purpose of phase-oriented electrical connection.
The circularly arranged slot apertures on the axially movable, spring loaded disc are preferably curved to correspond to the radius of the circle and align with correspondingly curved, U-shaped electrical metallic contacts, into which correspondingly curved blade-shaped contacts of the plug engage after penetrating the slot apertures of the disc during the rotation of the plug unit. A central bushing is formed coaxially to the casing of the body supporting the electrical contacts for the neutral conductor of the plug. The electrical contacts only first become operative during the further insertion and rotation of the plug. By rotating the plug, the circularly curved blade contacts enter into the corresponding U-shaped electrical contacts of the socket, whereby at the same time the projections on the plug which extend into the corresponding groove-shaped recesses of the socket housing reach a stop position, if a complete electrical contact is formed.
Due to the spring loading of the disc, the plug is finally pressed with its projections into corresponding depressions in the socket casing housing. These depressions are positioned laterally to the recesses so that a bayonet sealing connection results which prevents the removal of the plug. The removal of the plug is only possible if the plug is pressed into the socket, and then further turned for a certain angular range, which can amount to 30.degree.-40.degree..
The body with the electrical connections, likewise, is essentially circular in shape and represents a plate to which the electrical connections are attached. It is attached together with the housing which surrounds the body with, for example screws, to a ceiling or a wall, if desired.
Through the attachment of different connections to the plug which are wider or thicker, confusion of the electrical phases is precluded so that the invention is also suitable for either alternating or direct current, or for serial connections and the like. The locking position or the position in which the plug can be removed from the socket, may be marked on the plug and on the plug socket.
The plug itself essentially comprises two parts, one of which is a bowl-shaped round part which corresponds to the internal diameter of the housing of the socket and the electrical clamping contacts are attached on its interior. The blade-shaped contacts, which project through the base of the bowl-shaped part extend from these. Rectangular projections are formed on the external circumference of the bowl which are more or less wide or thick in the circumferential direction. These projections ensure the locking and the correct phase connections, as described above.
The bowl-shaped part is covered by means of a cover with a boring for the passage of the cable. A clamping device may be positioned on or in the boring for the purpose of traction relief of the cable, as well as a suspension, for example, of a bracket or a joint for a lamp. The cover may be connected with the bowl-shaped part by screws.
If desired, the entire combination can be sealed with O-rings or thick disc so that it can also be used in damp areas.